Bags of chewy Chips Ahoy! chocolate chip cookies are being recalled in the United States after an “unexpected solidified ingredient” has been found in some of them.

Mondelēz Global LLC, the parent company of Nabisco, released a recall notice for consumers on April 13 for the limited and voluntary recall of the cookies. Mondelēz Global has not specified what the solidified ingredient in the cookies is, but said there have been reports of potential adverse health effects.

The 13-ounce pack of cookies containing the UPC 044000032234 and use by dates on Sept. 7, Sept. 8, Sept. 14 and Sept. 15, should not be eaten. The dates are located on the top left of the packaging near the lift tab.

Anyone who may have purchased these chocolate chip cookies should not eat them and reach out to Mondelēz Global, which is headquartered in East Hanover Township, New Jersey.